Moritz Erhardt's father Hans-Georg Dieterle suspects the 21-year-old, who had epileptic episodes in the past, suffered a seizure in the shower and drowned. The episode, Diterle told the Observer, was brought on by exhaustion.

Dieterle said this might not have occurred had his son been working in his home country. "In Germany, everyone has the right to rest between shifts, from a trucker to a surgeon," he said.

Dieterle said his son had completed an internship with the KPMG consulting group in Frankfurt in 2012 which had been less taxing than the London placement in terms of hours worked. "I think he worked really hard there, but not so excessively [as in London]," he said.

Erhardt reportedly collapsed after three consecutive so-called "magic roundabouts" — he would take a taxi home at 5 in the morning only to have it wait for him to shower and shuttle him back to the office.

Dieterle told the Observer that he wasn't angry with the bank itself, adding that his son was enjoying the internship at BofA.

The bank, which was planning to offer Erhardt a full-time position after he graduated, called him a " a highly diligent intern at our company with a bright future." They have launched a working group to investigate conditions.